Arrays of molded male fastener elements, e.g., hooks are often formed integrally with a sheet-form base, to provide a sheet-form fastener component. This component can then be engaged with female fastener elements to form a “hook and loop” fastener. It is generally desirable that the fastener elements have good strength and toughness, so as to provide strong engagement during repeated use of the fastener.
Hook and loop fasteners have numerous applications, including the manufacture of automobile seats. In recent years, seats for cars and light trucks have been formed by molding a foam bun that will serve as the seat cushion, and then attaching a pre-stitched fabric cover to the foam bun. Often, the fabric cover is attached to the foam bun by insert molding touch fastener strips into the outer surface of the foam bun and attaching cooperating touch fastener strips to an inner surface of the fabric cover. Generally, the fastener strips are attached to the fabric cover along the seams where the cover is stitched together, and held in place by the seam stitching. The touch fastener strips allow the seat manufacturer to rapidly and semi-permanently attach the fabric cover to the foam bun by pulling the fabric cover over the foam bun and pressing the opposed touch fastener strips on the foam bun and fabric cover together.
The touch fastener strips on the foam bun are typically recessed in trenches, to allow the seams in the fabric cover to be indented below the surface of the seat cushion. Indenting the seams in this manner forms aesthetically appealing indented creases in the surface of the seat cushion upholstery for a tailored look. The trenches also accommodate the additional thickness of upholstery fabric that is created where the seam is stitched.
For example, a foam bun 10, shown in FIG. 1, includes a central, generally planar portion 12, and a pair of bolsters 14,16 disposed on either side of the central portion 12. The central portion 12, and bolsters 14,16 are separated by trenches 18 which define sweeping curves. Trenches 18 are located in the seat cushion at the point of change in curvature formed where the surface of bolsters 14,16 on the side of seat cushion 10 intersect central portion 12.
As shown in FIG. 2, touch fastener strips 24 are bonded to the bottom surface 17 of trenches 18, e.g., by insert molding the foam bun 10 onto the touch fastener strips 24 with hook elements 25 exposed for engagement with cooperative fastener strips 27 that are sewn to the fabric cover 29 along seams 31. Because the trenches 18 are indented below the surface 33 of the central portion 12, when the cooperative touch fastener loops 27 are pressed against the touch fastener strips 24 the double thickness of fabric 35 that is below seam 31 will be recessed in the trenches, resulting in a smooth outer surface at the seam area of the seat cover.
This attachment method works well for fabric covers having straight seams. However, if the fabric cover has seams that define sweeping curves, e.g., seams that have a curvature similar to that of trenches 18 in FIG. 1, problems can occur because as the touch fastener strip extends around the curve in the trench the strip will tend to buckle. Seat designs having curved seams have become increasingly popular in the automotive industry, and thus attempts have been made to address this problem. Some manufacturers have cut and pieced together short sections of straight touch fastener strips. Other manufacturers have cut out curved sections from wider strips of touch fastener material. Both methods can be inefficient, time consuming, can waste material, and can result in an undesirably high production cost.
In general, the attachment of a pre-stitched fabric cover to the foam bun requires considerable time, skill, and dexterity because space is tight, and alignment of the fabric over the bun is difficult, especially at trench edges 36 (FIG. 1).
There is a need in certain applications for fasteners that are simple to use, and when engaged, provide strength in a desired direction.
There is also a need to be able to consistently, and efficiently produce fastener components having differing functional characteristics, using techniques that require limited changeover in basic tooling, yet allow for adjustments to produce the desired fastener characteristics.